The present invention relates to an animal growth promoting process which utilizes certain forms of lysocellin as a growth-promoting substance in food-producing mammals.
A fairly comprehensive review of the various classes of polyether antibiotics is set forth in Westley, Adv. Appl. Microbiology 22, 177-223 (1977). Lysocellin falls into Class 2a as defined by Westley. Class 2a comprises divalent polyethers of a linear configuration which may contain from about two or about three tetrahydropyran and/or furan structures, up to three total ring structures and no nitrogen atoms. Table VIII of the Westley publication discloses the effective level of lysocellin as a coccidiostat. Lysocellin at 300 ppm in feed was said to be effective against Eimeria tenella. The reference refers to the use of lysocellin in poultry feed, and the level of lysocellin required to function as a coccidiostat considerably greater than other polyether antibiotics, such as monensin, nigericin, lasalocid and others.
Lysocellin was first reported in the literature by Ebata, et al, The Journal of Antibiotics 28(2):118-121, 1975. The physico-chemical properties of lysocellin are described there, including a melting point of about 158.degree.-160.degree. C. of the colorless needles of the sodium salt. The antibiotic is said to be produced from a mutant strain of Streptomyces cacaoi var. asoensis designated Streptomyces cacaoi var. asoensis K-9 Met-, but this strain has apparently not been made available to the public. This reference discloses that lysocellin is active against gram-positive bacteria, antibiotic resistant Staphylococcus aureus, some fungi, but that it is not active against gram-negative bacteria. There is no disclosure here of any use of lysocellin in meat-producing animals.
The structural formula for lysocellin was set forth by Otake, et al, Agric. Biol. Chem. 42(10): 1879-1887, 1978. This reference also reports that lysocellin is effective in treating coccidial infections in poultry, but there is no mention here of any other use of lysocellin in meat-producing animals.
U.S. Pat. No. 4,033,823 issued July 3, 1977, to Liu, et al, discloses the structural formula of lysocellin and a method for making it using Streptomyces longwoodensis (ATCC 29251). This patent only describes the use of lysocellin as an antimicrobial.
More recently, lysocellin was compared to a number of other polyether antibiotics for inhibition of ruminal degradation of L-tryptophan (TRP) to 3-methylindole (3MI) in vitro. Other polyether antibiotics used for the comparison included desoxysalinomycin, X-206, nigericin, lasalocid, monensin, narasin and salinomycin. Chloral hydrate was also used. The study was aimed at determining the potential effect of these antibiotics in the treatment of acute bovine pulmonary edema and emphysema (ABPE), or "fog fever", which appears to relate to ruminal production of 3MI. Hammond, et al, Journal of Animal Science 51(1): 207-214, 1980.
The above study by Hammond, et al, reported that the polyether antibiotics tested were the most effective compounds in reducing in vitro ruminal degradation of TRP to 3MI without significant decrease in VFA production. However, lysocellin was reported as one of the least effective of the polyether antibiotics tested for this purpose. This publication concludes that "further investigations of the effects of monensin on live animals are warranted". No further work with lysocellin was recommended by the authors. It should be noted that monensin did depress the VFA production in this test, and that its use as a feed additive is only for improved feed efficiency or utilization. See: U.S. Pat. No. 3,839,557.
U.S. Pat. No. 4,129,578 discloses the use of Compound 38,295 (etheromycin) as having anticoccidial, antimicrobial and growth promotant properties. Various cationic salts of etheromycin are disclosed, including copper, zinc, ammonium, calcium, magnesium and lithium salts. However, the microorganism, Streptomyces hygroscopicus ATCC 31050 used in the above reference has been withdrawn from the culture collection, so the reference is not believed to be "enabling" as to the growth promoting effects disclosed. In any event, the patent discloses only the use of etheromycin (Antibiotic 38,295 derived from ATCC 31050).
Recently issued U.S. Pat. No. 4,221,724 Liu et al, discloses the use of polyether antibiotic X-14766A as a growth promotant for ruminants. However, the only results reported in this patent were for in vitro volatile fatty acid production. Although such tests may give an indication that a substance will be effective as a growth promotant in ruminants, this is not conclusive, and actual in vivo testing is necessary. The molecular structure of X-14766A is different from lysocellin. X-l4766A includes a chloride group on a methylbenzoic acid group, there are forty-three carbon atoms in the molecule, and there are four successive heterocyclic polyether rings, whereas lysocellin contains only two successive heterocyclic polyether rings, contains neither chloride groups, nor a methylbenzoic acid group. In addition, lysocellin has a total of only thirty-four carbon atoms in the molecule.
It has now been surprisingly discovered that the various forms of lysocellin act as especially effective growth-promoting and feed efficiency-enhancing agents when administered to food-producing mammals such as ruminants. In ruminants having a developed rumen function, including cattle, sheep and goats, the various forms of lysocellin are believed to promote growth and enhance the efficiency of feed utilization in the animal by lowering the acetate/propionate ratio among the volatile fatty acids (VFA) found in the animal's rumen fluid. The relationship between acetate/propionate ratio in the rumen and feed efficiency in the ruminant animals is explained in greater detail in Raun, U.S. Pat. No. 3,794,732 issued Feb. 26, 1974.
Therefore, the present invention relates to processes for promoting growth and enhancing feeding efficiency in food-producing mammals by administering various forms of lysocellin to meat-producing animals, particularly ruminants. Among the useful forms of lysocellin are: the free acid and the pharmaceutically acceptable salts, including sodium, zinc, manganese, magnesium and copper salts. Zinc, manganese and copper are believed to form salt "complexes", and two of the linear polyether molecules "wrap" around the bivalent cation.
In accordance with the present invention, the zinc, manganese, or copper complexes of lysocellin can be formed by adding water-soluble zinc, manganese or copper salts to the fermentation broth in which lysocellin has been prepared, and the resulting broth-insoluble zinc, manganese or copper complexes of lysocellin can then be recovered from the broth and employed as growth-promoting and feed efficiency enhancing additives, especially in feed for food-producing mammals such as ruminants, swine and poultry.
Lysocellin-containing fermentation broth is prepared in conventional manner by fermenting a nutrient-containing liquid fermentation medium inoculated with a Streptomyces longwoodensis (ATCC 29251) which is capable of producing lysocellin. Suitable liquid fermentation media are generally aqueous dispersions containing a nitrogen source and a carbohydrate source. Nitrogen sources for use in the fermentation media herein can include, for example, sugar, molasses, cornsteep liquor and the like. The fermentation media can also contain a variety of optional ingredients, if desired, such as for example, pH adjustment agents, buffers, trace minerals, antifoam agents, filter aids, etc.
The Streptomyces microorganism is grown in an aerated, agitated, submerged culture with the pH of the broth adjusted to about neutral, i.e., from a pH value of about 6.5 to about 7.5. Fermentation can generally be carried out at slightly elevated temperatures, e.g., between about 25.degree. C. and 35.degree. C. Incubation of the broth can be carried out for a period of several days, e.g., from about 4 to 6 days or longer if it is economically advantageous to do so.
A particular method for producing the antibiotic lysocellin was disclosed by Liu et al in U.S. Pat. No. 4,033,823 by the cultivation of a strain of Streptomyces longwoodensis which is on unrestricted deposit at the American Type Culture Collection under the designation ATCC 29251. The structure of lysocellin is as follows: ##STR1## Suitable methods for preparing the lysocellin antibiotic are set forth in the above-mentioned patent. The characteristics of lysocellin were first set forth in the article by Ebata et al, J. Antibiotics 28:118-121, 1975.
The various forms of lysocellin, including the free acid, sodium salts, and the zinc, manganese, and copper lysocellin complexes used in the present invention act as growthpromoting agents in food-producing mammals, e.g., ruminants, swine and poultry. These forms of lysocellin can be administered to food-producing animals, either orally, subcutaneously or parenterally, in amounts sufficient to enhance the growth rate of the animal. The amount of the lysocellin material administered to an animal varies, of course, with the species of animal, the desired rate of growth, and the like. The material is frequently administered to ruminants in an amount of about 1 to 200, preferably about 1 to 50 milligrams per head per day.
Preferably, the lysocellin material is administered to food-producing animals in their feed, and can be conveniently added to animal feed in the form of the dried, antibiotic-containing biomass which is recovered as a feed additive composition from the fermentation broth as hereinbefore described. It may also be administered in liquid feeds, and in the animal's drinking water.
A feed composition may be prepared containing the usual nutritionally-balanced quantities of carbohydrates, proteins, vitamins and minerals as diluents together with the lysocellin material. Some of the usual sources of these dietary elements are grains, such as ground grain and grain by-products; animal protein substances, such as those found in fish meal and meat scraps; vegetable proteins, such as soybean oil meal or peanut oil meal; vitaminaceous materials, e.g., mixture of vitamins A and D, riboflavin supplements and other vitamin B complex members; and bone meal and limestone to provide minerals. A type of conventional feed material for use with cattle, for example, includes alfalfa hay and ground corn cobs, together with supplementary vitaminaceous substances if desired. The lysocellin materials of the present invention can generally be employed in the feed compositions to the extent of from about 15 grams per ton to 200 grams per ton, preferably from about 75 grams per ton to 125 grams per ton.
The lysocellin growth-promoting agents described herein, can also be administered to food-producing animals subcutaneously or parenterally in combination with a pharmaceutically-acceptable carrier. For example, the lysocellin materials can be employed in an injection composition, or as an implant under the skin. Administration of the growthpromoting agents herein in this manner can include intramuscular, intravenous, subcutaneous, and intraperitoneal injections. When an implant is used, for example, a ball or cylindrical implant inserted under the skin on the ear of an animal, the implant will generally contain from about 1 mg to 100 mg of one of the lysocellin materials.
The various lysocellin materials, their preparation and recovery and the feed and feed additive compositions involved in the present invention as well as their usefulness as growth promoting agents for ruminants are illustrated by the following examples. Such examples include the preparation, recovery and evaluation of the preferred lysocellin material, but are in no way limiting of the present invention to processes involving that particular material.